It is well known in the art to attach the individual trim panels of a trim panel assembly by a process known as staking. In such a process, one of the parts to be joined has an aperture while the other part includes an elongated protrusion sized to fit through the aperture. Pressure is then applied to compress the protrusion radially forming an interference fit between the two parts.
As the individual trim panels of a trim panel assembly are often formed of a molded plastic, a variation of the staking process known as thermoplastic or heat staking is used. The heat staking process uses heat to soften the plastic protrusion and pressure to compress the protrusion forming a head which mechanically locks the two panels together.
As such, heat staking is a versatile process allowing the simultaneous formation of several heads by deforming several protrusions. Trim panel assemblies which are composed of several individual trim panels are particularly well suited to the heat staking process as the multitude of protrusions of the individual panels can be simultaneously deformed thereby assembling the trim panel assembly in one step. However, trim panel assemblies often include overlapping trim panels which may or may not require all of the overlapping panels to be attached. In many instances the trim panel assembly only requires that the outer two overlapping panels be attached even though there is a third overlapping panel.
As the heat staking process utilizes a weld horn to apply heat and then pressure to compress the softened protrusion, a weld horn backing plate is placed behind the panels to provide rigid support during the heat staking process. However, if only the two outer panels are to be attached and there is a third overlapping panel, it is the third overlapping panel which would contact the weld horn backing plate. As such, the two outer panels to be attached are left unsupported.
In such a circumstance it is known in the art to provide a support extending from the third overlapping panel which abuts one of the panels to be attached thereby providing support. However, a problem arises when the distance between the third overlapping panel and one of the panels to be attached extends beyond a certain point. As the individual trim panels are formed of a molded plastic, extending the support to such a point will cause surface defects on the opposite side of the trim panel. This is unacceptable as the opposite surface of the third overlapping panel faces the interior passenger compartment of the automotive vehicle.
Thus, there exists a need for an improved trim panel assembly having a structure capable of providing support during a heat staking process.